Miniaturization of cylindrical ion trap mass analyzers

The cylindrical ion trap (CIT) mass analyzer has received considerable attention due to the ease of fabrication and its potential advantages including operating on high pressure, low voltage, and power consumption. It has been proven to be a promising mass analyzer for miniature mass spectrometers (MS) as a useful tool for in-field measurements. The miniaturization process of the CIT from centimeter to micrometer-scale has been realized by micro-fabrication techniques, revealing the development of CIT-MS towards hand-held. The array of CITs provides an efficient method to increase its trapping capacity, which can be coupled to various ion sources for expected applications. The special/general applications of miniature CIT mass spectrometers have been widely explored, such as volatile organic compounds in human breath, explosives, chemical warfare agents, etc. In this paper, we review the characteristics and history of CIT mass analyzers including single and arrays of CITs, and address their practical applications. We also describe the current CIT mass spectrometers and discuss their development.